Friction clutch



0d. 31, 1939. A H, R FEDDEN ET AL 2,178,017

FRICTICN CLUTCH y Filed March 24, 1939 f www.

Patented octal, 1939 2,178,0l7

FRICTIN CLUTCH Alfred Hubert itoy Fedden and .lames Lansdowne Norton, Bristol, England, assignors to The Bristcl Aeroplane Company Limited, Bristol, England, a British company Application March 24, 1939, Serial No. 263,978 ln Great Britain April 9, 1938 7 Claims. (Cl. 15%2-86) This invention is for improvements in fricdrawing showing vthe parts in the positions they tion-clutch mechanism of the kind in which the `assume when the clutch is disengaged, and the engagement and/or disengagement of the clutch bottom half of the drawing showing the same is effected by a reciprocating hydraulic motor. parts in the positions. they assume when the The object of the invention is to provide a comclutch is engaged, and

pact design of clutch-mechanism of this kind. Figure 2 is a sectional elevation on the line According to the invention, friction-clutch 2 2 of Figure 1 showing one half, only, of the mechanism of the kind described comprises a assemblage. hydraulic cylinder, a relatively reciprocable pis- As shown in the drawing, a xed hollow spinton within the cylinder, which piston divides the die I@ is mounted in frame members l l, l2, being i0 cylinder space into two chambers, one on each separated therefrom by bushings i3, i4. At the Side of the piston, co-operating clutch members left-hand end of the spindle i0 it is engaged by housed in one of said chambers so as to be ima tubular plug l5 screw-threaded into it and mersed in the pressure-liquid admitted to that formed with a nut-portion it. At its right-hand side of the piston, and means operated automatiend the plug l5 is formed with an enlargement l1 D cally by relative movement between the cylinder which makes fluid-tight engagement with a porand piston to drain the said chamber of liquid, tion I8, of the spindle ill, of reduced diameter. 'at least when the said clutch members are disen- To they left of these interengaging portions it gaged. By housing the clutch members within will be seen that the tube l5 is spaced away from 2 0 the hydraulic cylinder a very compact arrangethe surrounding bore of the spindle so as to leave 20 ment of the parts is made possible.V However, a tubular space i9. This space constitutes an oil but for the present invention, the clutch memconduit as described below. At its right-hand bers would be immersed in the pressure liquid end, the spindle l0 is closed by a plug 2li So aS t0 when the clutch members were disengaged and form a Space 2l in COmmullCaiOIl With the i11- ysuch immersion would give'rise to drag between terior of the tube l5. 25 them. Preferably the arrangement is such that, At its left-handend, the wall of the tube l5 is to disengage the clutch, liquid is admitted to the formed with radial passages 22 'communicating chamber containing the clutch members. with a surrounding annular Chamber 23 into The liquid may be drained away through a port which a conduit 24 leads, the conduit being cast which may or maynot be controlled, or may be in the frame membery l2. To the right 0f the 30 partly controlled, by the relative movement be- Screw-threads 25, by which the tube l5 engages tween the cylinder and piston. In order to cut the spindle Ml, the spindle is formed with a radial 01T the admission of liquid to the chamber when port 26 which communicates, by Way 0f a C0- the disengaging movement has ceased the said Operating DON 1'1'1 the bUShIlg i4, With a Conduit relative movement may also close an inlet port 2l also cast in the frame member l2. From the 35 in the cylinder or piston. above descriptionit will be clear that the conduit The mechanism preferably comprises a driving 24 communicates by way of the chamber 23, the shaft, a driven gear rotatably mounted on the ports 22 and the bore 0f the tube l5 with the Space said shaft, a hydraulic cylinder carried by the 2l at the right-hand end cf the spindle; and that said driven gear, clutch members within the cylthe conduit 21 communicates byway of the port 40 inder, a piston within the cylinder for engaging 2S with the tubular space i9 at the left-hand end the clutch members, and means for draining liqof the spindle. uid from the cylinder when the clutch is engaged, Surrounding the spindle il! is a tubular shaft The mechanism preferably comprisesaxed spin- 28 which is integrally formed at its left-hand' rdle within the shaft, a space at one end of the end with a pinion 29 by which it is driven. A 45 spindle communicating with one end of the eyl' lining 3@ of bearing metal is inserted .from the inder, a space at the other end communicating right-hand end and is locked so as to rotate with with the other end of the cylinder and conduits the shaft by means of a dowel 3l. At the left-- leading into said spaces both from one end of hand end a similar lining 32 is provided, being the spindle. secured to the shaft 28 by a similar dowel (not 50 A specific embodiment of the invention vwill shown). A roller bearing 33 is provided between now be described by way of example with referthe pinion 29 and the spindle l0 for the leftence to the accompanying drawing: khand end of the shaft 2d; the bearing surface Figure 1 is a sectional elevation of a clutch for the remainder of the shaft is aiorded by the accordngtc the invention, the top half of the internal surface of the bushings 30 and 32. 55

Rotatably mounted upon the shaft 28 is a hydraulic cylinder comprising two parts; a leithand annular wall 34 which has integrally formed with it a cylindrical wall 35 and which is borne on the shaft by a roller bearing 38 engaging an outer race 31, and a right-hand annular wall 38 which is borne on the shaft by a roller bearing 39 having an inner race 48 locked on the shaft by means of a nut 4I on the right-hand side, between which and a collar 42 on the left-hand side the race is clamped. The collar 42 abuts against a shoulder on the shaft 28 and is formed with a plate-like portion 43 the purpose of which will be described below. The wall 33 of the cylinder is integrally formed with gear-teeth 44 which transmit the drive when the clutch is er1- gaged. The wall 38 is attached to the cylindrical wall 35 of the other part of the cylinder by suitable bolts 45, only one of which is shown.

IThe clutch-plates are situated at the righthand end of the hydraulic cylinder above described. ri'he driving clutch-plates 4'45,k 41, are annular in shape and at their inner edges are formed with castellations to engage cooperating splines 48 formed on the shaft 28. The castellations 48a of the clutch-plate 48 are shown in Figure 2 and the castellations on the clutch-plate 41 are similar. Thus, the clutch-plates 48 and 41 are slidable along the shaft 28 but are non-,rotatable with respect tc it.

The driven clutch-plates 49, 59 are formed with castellations which inter-engage with splines cut on the internal wall of the cylindrical wall 35 of the hydraulic cylinder. The gaps between the splines 5I are engaged alternately by the castellations 52 (Figure 2) on the clutch-plate 49, and by similar castellations (not shown in Figure 2) cn the clutch-plate 58. Thus, the plates 49 and 58 are slidable along the cylinder wall 35 but are non-rotatable with respect thereto.

Means for ensuring separation of the clutchplates when the clutch is disengaged, and for limiting their separating movement, will now be described. Between the annular plate 43 of the collar 42 and the clutch-plate 41 is a spring 53 in the form of a fiat circular ring which is waved in the view of Figure l so as to be compressible by attening in a direction longitudinally of the axis of the clutch. The eiect of the spring 53 is to tend to press the plate 41 towards the left, but its movement in this direction is limited by means of stops 55, of which there may be three symmetrically arranged around the shaft axis, each lying between two adjacent splines 48 as shown in Figure 2. The clutch-plate 46 is pressed towards the left by means of a wavy spring 56 lying between the clutch-plates 46 and 41. spring 55 is formed with inward projections 55i which lie between adjacent splines 48 on the shaft E8 as shown in Figure 2, whereby the spring is nonrotatable with respect to the shaft. The spring 53 between the clutch-plate 41 and the plate 43 is similarly formed with such projections which are indicated by the reference 51 in Figure l but are nct Visible in Figure 2. The movement of the clutch-plate 48 towards the left is limited by the engagement of its castellations 49a with the unsplined shoulder 58 on the shaft which shoulder also forms an abutment for the stops 55.

The driven clutch-plate 59 is pressed towards the left by a double wavy spring 59 lying between it and the annular wall 38. Movement of this clutch-plate towards the left is limited by stops 58 each arranged between two adjacent splines 5l on the cylindrical wall 35, as shown in Figure 2, and each abutting at its left-hand end against an internal flange 6i (Figure l). The other driven clutch-plate 49 is pressed towards the left by means of a wavy spring 62 which lies between it and the clutch-plate 59. rlhe spring is formed at one or more points on its outer edge with outwardly extending projections 63, each of which lies between adjacent splines 5l on the cylindrical wall of the hydraulic cylinder so as to lock the spring against rotation with respect to the cylinder. Similar projections may be provided on the springs 59.

Movement of the clutch-plate 49 towards the left is unlimited except by the hydraulic piston which will now be described.

The piston 84 is formed on its right-hand face with a series of arcuate projections 55 to abut against the driven clutch-plate 49. The outer wall of the piston carries piston rings 66, 51, which co-operate with grooves and ports, in the cylinder wall, described below. The inner wall 83 of the piston slides on a packing ring 89 housed in a groove in the shaft 28. The wall 68, together with a tubular extension 98 on the righthand side of the piston, constitute a slide-valve, the two tubular portions being separated by a groove 16. riChe groove all communicates by ports 1l with the right-hand side of the piston and c0- operates with a series of radial holes 12 in the shaft 28 in a manner described below.

rihe cylindrical wall 35 oi the hydraulic cylinder is formed with a plurality of ports 13; for example, there may be six such ports, symmetrically arranged. At the right-hand side of the ports i3 the inner wall of the cylinder is cut with two grooves 14 each of which leads into an adjacent port 13. At the left-hand side the wall of the cylinder is cut with grooves which, however, do not lead into the adjacent ports' 13 but '1 are separated therefrom by an uninterrupted land 16. The grooves 14 and 15 provide leakage paths of restricted cross-section for a purpose which will appear below.

The piston 64 is pressed towards the right by a wavy spring 11 lying between it and the annular wall 34 of the hydraulic cylinder, ythe spring being keyed against rotation with respect to the piston by an inturned tongue 95 which engages a illing 18 of light metal riveted to the left-hand side of the piston in order to reduce the Volume of the left-hand chamber.

The tubular space i9 in the spindle I9 leads by way of radial ports 19 in the spindle into a continuous groove 88 cut on the inner wall of the lining 38. This lining is formed with ports 8l which lead into radial holes 82 in the shaft 28, the holes opening into the hydraulic cylinder on the left-hand side of the piston. Leakage from this side of the piston is prevented bya packing ring 83 housed in a groove in the shaft and engaging a ange formed on the roller race 31.

The space 2l at the right-hand end of the spindle communicates through radial holes 84 formed in the spindle i9 with a continuous groove 85 formed in the lining 38 which communicates through ports 86 with the radial holes 12, above described, in the shaft 28.

The purpose of making the grooves 8U and 85 rather longer, in a direction parallel with the axis of the spindle I8, than appears necessary, is to provide a separate supply of oil to the various surfaces requiring lubrication. The lubrication system, however, forms no part of the invention and is therefore not illustrated in the drawing.

The operation .of the apparatus above described is as follows: If the clutch is disengaged, as shown inthe vtop halfof Figure l, and it is required to engage the clutch, oil under pressure is admitted to the conduit 2'! by the operation of a sirltable valve (not shown), and the conduit 2li is connected to a drain. The oil under pressure flows from the space i9 through the ports '19, 82 to the left-hand side of the piston. Slight leakage occurs along the grooves 'l5 and out through the holes 73 in the cylinder wall, but such leakage is not suilicient to cause any material delay in the building up or" pressure on the left-hand side of the piston. Such pressure therefore forces the piston to the right; the projections E5 engage the clutch-plate $9 whereby all four clutch-plates are pressed together as shown at the bottom of Figure l. When the piston reaches the end of its stroke the piston ring @t engages the land 'i6 whereby further leakage of oil along the grooves 'i5 is prevented. When the parts are in the position shown at the bottom of Figure l, the righthand chamber is empty of oil (for reasons explained below), so that the centrifugal force on the oil on the left of the piston augments the clutch-engaging force. Any oil which leaks into the right-hand chamber, when the clutch is engaged, will leal; out along the grooves l. There is thus no tendency for oil to accumulate in the right-hand chamber.

When the clutch is engaged, it will be seen that the groove 'lll in the piston registers with the ports 'i2 in the shaft 2S. If it is now required to disengage the clutch oil under pressure is admitted to the conduit 24 and the conduit 2'! is connected to the drain. The oil under pressure flows from the chamber 2i through the ports T2 into the groove TQ, along the ports 'il in the piston to the right-hand chamber. The oil fills the chamber containing the clutch-plates and tends to leak away along the two grooves 74 and through the holes '13. However, the outlet area which these grooves provide is too small to cause any material delay in the building up of pressure in the right-hand chamber so that the piston is moved towards the left. The various springs above described cause the clutch-plates to separate whereby the clutch is disengaged.

The slide valve 9B, when the piston approaches the end of its stroke towards the left, closes the outlet from the radial ports 7E, whereby the flow of oil into the right-hand chamber ceases. At the same time the piston ring 61 opens the comparatively large holes 'H3 in the cylindrical Wall 35, whereby substantially all the oil in the righthand chamber is discharged through these holes. The flow of oil from between the clutch-plates to the holes 73 is facilitated by perforating the clutch-plates 46 and 4'! as shown at 9i and the clutch-plates fl and 5B as shown at S2, and by the spacing apart of the projections 65 in a peripheral direction as shown in Figure 2. Thus, shortly after the parts have reached the positions shown in the top halt of Figure 1, the right-hand chamber will be almost completely drained of oil so that the movement of the driving clutch-plates d6, dl, With respect to the now stationary driven clutch-plates 49, 5t, will not be impeded by the drag of films of oil between them.

It will be understood that the gear-wheel dit is now stationary although the shaft 28 and associated parts continue to rotate.

If, for any reason other than deliberate actuation oi the control valve, the piston now tends to move towards the right so as to engage the clutch, the vleft-hand edge of the slide valve 90 again opens the ports 'l2 and the piston ring 67 closes the holes 'E3 except for the narrow route along the grooves M, so that oil is again admitted to the right-hand chamber and the piston pressed back to the position shown in the top half of Figure 1.

When the clutch is being disengaged as above described, the oil from the left-hand chamber is :forced out by the piston through the ports 82, 19, and along the duct 2l. When the parts reach the positions shown in the top half of Figure l, the piston ring 66 registers with the grooved portions 'I5 of the cylinder wall so that oil remaining in the left-hand chamber leaks away along the grooves le and through the holes '13. Thus, when the clutch has been disengaged, both chambers are empty of oil.

The invention may be applied to a supercharger, driven by gearing from an internal-combustion engine, in which the supercharger drive is required to be engaged and disengaged at will. In particular, the clutch according to the invention may be incorporated in the drive to the rststage blower of a two-stage supercharging system. The gearing is contained in an outer casing which receives the oil discharged through the holes i3 and returns it to a sump.

We claim: y,

l. Friction-clutch mechanism comprising a h ydraulic cylinder rotatably mounted upon a coaxial shaft, a piston slidable along the shaft within the cylinder, a clutch-member non-rotatably mounted with respect to the cylinder and another clutch member non-rotatably mounted with respect to the shaft, the said clutch members being so arranged in a chamber between the piston and one end of the cylinder as to be engaged by movement of the piston towards that end, one or more inlet ports in the said shaft for the admission of pressure-liquid to the chamber and one or more outlet ports in the cylinder for the discharge of liquid from the chamber, the said inlet and outlet ports'being so arranged in relation to the piston as to be closed and opened respectively when the clutch has been disengaged.

2. Friction-clutch mechanism comprising a hydraulic cylinder, a relatively reciprocable piston within the cylinder, which piston divides the cylinder space into two chambers one on each side of the piston, co-operating clutch members housed in one oi said chambers, means for admitting pressure-liquid to said chamber to disengage the clutch, and means operated automatically by relative movement by the piston and cylinder to drain the said chamber of liquid, both when the clutch has been disengaged and when the clutch has been engaged.

3. Friction-clutch mechanism comprising a hydraulic cylinder rotatably mounted upon a coaxial shaft, a piston slidable along the shaft within the cylinder, a clutch member non-rotatably mounted with respect to the cylinder and another clutch member non-rotatably mounted with respect to the shaft, the said clutch members being so arranged in a chamber between the piston and one end of the cylinder as to be engaged by movement of the piston towards that end, one ror more inlet ports in the said shaft for the admission of pressure-liquid to the chamber, and a sleeve around the shaft, carried by the piston and formed with an internal groove communicating with the clutch-side of the piston by one or more ports in the piston, whereby the said groove registers with the said inlet ports when the clutch is engaged, so that liquid may be admitted to disengage the clutch, and whereby the sleeve closes the said ports when the clutch is disengaged so that the chamber may be drained of liquid.

4. Friction-clutch mechanism comprising a hydraulic cylinder rotatably mounted upon a coaxial shaft, a piston slidable along the shaft within the cylinder, a clutch member non-rotatably mounted with respect to the cylinder and another clutch member non-rotatably mounted with respect to the shaft, the said clutch members being so arranged in a chamber between the piston and one end of the cylinder as to be engaged by movement of the piston towards that end, one or more permanently-open inlet ports from the shaft to a chamber between the piston and the other end of the cylinder, and one or more outlet conduits of restricted cross-section from said chamber, said outlet conduits being so arranged as to be closed by the piston when the piston reaches its clutch-engaging position.

5, Friction-clutch mechanism comprising a hydraulic cylinder rotatably mounted upon a coaxial shaft, a piston slidable along the shaft within the cylinder, a clutch member non-rotatably mounted with respect to the cylinder and another clutch member non-rotatably mounted with respect to the shaft, the said clutch members being so arranged in a chamber between the piston and one end of the cylinder as to be engaged by movement of the piston towards that end, one or more grooves of restricted cross-section formed in the cylinder wall, which grooves, when the clutch is disengaged, communicate with outlet ports at a point in the wall of the cylinder between the piston and the other end of the cylinder, and a piston-ring which when the clutch is engaged, co-operates with an ungrooved portion of the cylinder wall lying between the said grooves at the said ports.

6. Clutch-mechanism as claimed in claim 1, wherein the said chamber is permanently open to the said outlet ports through conduits of restricted cross-section whereby liquid is prevented from accumulating in the chamber when the clutch is engaged.

7. Clutch-mechanism as claimed in claim 1, comprising a xed spindle within the said shaft, a space at one end of the spindle communicating with one end of the cylinder, a space at the other and communicating with the other end of the cylinder and conduits leading into said spaces both from one end of the spindle.

ALFRED HUBERT ROY FEDDEN. JAMES LANSDOWNE NORTON. 

